Electric cut-out



(No Model.)

N. MARSHALL. ELECTRIC GUT-OUT.

No. 588,686. Patented Aug. 24,1897.

INVENTUR. WM

y Mwuwm ATTY UNITED STATES PATENT OFFICE.

NORMAN MARSHALL, OF BOSTON, MASSACHUSE'ITS.

ELECTRIC CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 588,686, dated August24, 1897. Application filed May 29,1896. Serial No. 593,570. (No model.)

To all whom it may concern:

Be it known that I, NORMAN MARSHALL, residing in Boston, county ofSuffolk, and State of Massachusetts, have invented an Improvement inElectric Cut-Outs, ofwhich the following description, in connection withthe accompanying drawings, is a specification, like letters and numeralson the drawings representing like parts.

This invention relates to a novel method and apparatus for interruptingelectric arcs between two terminals normally connected by fusiblematerial, which apparatus is commonly known as fusiblecircuit-controllers or cutouts. These circuit-controllers as nowcommonly constructed consist of sections of fusible material, usuallymetal, interposed between and connecting circuit-terminals secured to asuitable support or base usually made of porcelain or other suitablematerial.

The fusible material, commonly termed the fuse, is designed to carry agiven or predetermined amount of current without rupture, but is alsodesigned to be melted and ruptured by an abnormal current. Fusiblecircuit-controllers of the class referred to as now commonly constructedand known to me have been found in practice to be efficient for thepurpose intended when the circuit is traversed by a current whosepotential is not largely in excess of the carrying capacity of the fuse,but when the said circuit is traversed by a current of excessivepotential such, for instance, as five hundred to two thousand volts-thefuse becomes defective because of the formation of an are between theline-terminals to which the fuse is normally connected, so thatnotwithstanding the fact that the fuse has been melted the circuit ismaintained by the arc and the abnormally high current continues to flowover the circuit to the detriment and oftentimes destruction of theinstruments or translating devices in the said circuit, and the said areis also a source of destructive tires.

This invention has for its object to provide a fuse cut-out orcircuit-controller in which an are which might be formed between theline-terminals may be broken and destroyed by a current of gas or heatedair generated or created by the heat developed by the melting of thefuse and the arc itself and directed or projected across the path orplane of the said arc at a point different from that at which thepressure is created. The fuse may be of any suitable or usualconstruction, but preferably will be of a construction as will bedescribed, whereby the action of the gaseous current created by themelting of the said fuse may work with certainty and with the highestefliciency.

These and other features of this invention will be pointed out in theclaims at the end of this specification.

Figure 1 is a top or plan view of one form of fusible cut-out orcircuit-controller embodying this invention. Fig. 2 is a longitudinalsection of the cut-out shown in Fig. 1 011 the line 2 2; Fig. 3, a topor plan view of the cut-out shown in Fig. 1 with the cover or top plateremoved; and Fig. 4, a transverse section on the line i at, Fig. 3,looking toward the right.

In the present instance I have shown one form of cut-out orcircuit-controller embodying this invention, in which A represents abase or support, which may be made of porcelain, hard rubber, or othersuitable material and which is herein shown as substantially oblong inshape and provided with the bottom a, side walls a a and end walls a a,forming a trough-like or box-shaped base or support.

The base or support A has secured to it, preferably at or near itsopposite ends, as by screws a a, suitable terminals a a preferably flatpieces of metal, which are herein shown as secured to the bottom a andhave fastened to them, as by binding-screws a a the line or circuitwires (0 a, which may be of any suitable or desired construction.

The line-terminals a a are electrically connected by a fuse, which maybe of any suitable or desired construction, usually a piece or strip Z)of metal or composition of metals, fastened to the line-terminals a a asherein shown, by screws a a.

In accordance with this invention the strip 1) extends or is laid acrossone or more substantially small or contracted gas or air outlet passagesor discharge-openings for a substantially large chamber intermediate ofthe line -terminals and having a substantially large opening distinctfrom the discharge openings, and in the present instance the said stripis laid or extended across two outletpassages 1) '0 located in thepresent instance at the opposite ends of the chamber B, which may beformed, as herein shown, by cross par titions or walls b b and top wallsb 1), extended toward each other, but separated, as herein shown, toleave a substantially central opening b which is normally closed by aremovable cover or top piece b for the base or support A. The chamber Bmay also have extended partially across it, as shown, a wall orpartition Z), preferably extended beyond the longitudinal center of thesaid base or support, and around the end or side of which the fuse Z) iscarried, as shown in Fig. 2,.

The cover b may be secured to the base or support A by a screw 1)extended through the cover and through a suitable hole in the wall orpartition I), and the said screw may have its lower end extended into ahole in the base A and provided with a suitable nut 1), preferablysealed within the hole in the base by insulating material Z1 The sidewalls a a of the base A may be provided with suitable ledges b 12 uponwhich rests the cover 6 the latter also resting, as herein shown, uponthe walls 11 I) b. The top walls b b of the chamber B may be pro videdwith longitudinal grooves I) If, in which the fuse-wire may be laid.

By reference to Fig. 2 it will be seen that with the construction hereinrepresented the chamber 13 is substantially a closed chamber when thecover b is in place and that the passages l) b form discharge openingsor outlets transverse to the fuse and that these outlets substantiallyregister or are in line with slots or passages c c in the cover 11 Theoperation of the cut-out or circuit-controller herein shown is asfollows: The circuit is maintained by the fuse I) while a current ofnormal strength is flowing over the line-say, for instance, a current ofone hundred and ten volts; but if the current is increasedabnormally-as, for instance, by the circuit-wires a to becoming crossedwith a line carrying five hundred or more volts-the fusebis melted bythe abnormal current and the air in the chamber B is expanded by theheat generated by the heating and melting of the fuse l), and the saidexpanded air seeking an outlet is forced through the substantiallynarrow dis charge outlets or passages l) b for the chamber B andinterrupts or breaks the are which might be formed between the terminalsa cv, thus opening the circuit, and thereby protecting the instrumenttherein and preventing fires being started by the said are, andconsequently reducing the danger of fire from this source, which at thepresent time is an important item, owing to the growing demand and useof high potential currents. In order to increase the efficiency of thecut-out and render the same more certain to break the are, I prefer tomake the fuse D so that it will re spend to or be first melted by theabnormal current in the immediate vicinity of the discharge-outlets forthe chamber B, and this result may be accomplished by making the fuse bthinner or weaker, as at 2 3.

I may prefer to make the fuse-block or cutout as herein shown; but I amaware that this construction may be varied without departing from myinvention, which resides, essentially, in the interruption of the are bya current of air or gas created by theheat generated by the melting ofthe fuse and by the are itself, and therefore I do not desire to limitmy invention to the particular apparatus herein shown. The chamber 13,as herein shown, is provided with two outlets, and while I prefer thisconstruction only one such outlet may be advantageously used.

I claim- 1. The method of interrupting electric arcs formed between twocircuit-terminals normally connected by fusible material, which consistsin creating a substantially large gaseous or air pressure by the heatgenerated by the melting of the said fusible material and consequentformation of the are, and causing the same to pass in a smaller orrestricted amount across the plane or path of the are formed between thesaid terminals at a different point from that at which the pressure iscreated, substantially as described.

2. In an electric'cut-out or circuit-controller, a base having securedto it circuit-terminals, and provided with a chamber intermediate ofsaid terminals and having a substantially large opening and a separateand restricted discharge-outlet, and a fuse normally connecting saidterminals and extended across said discharge-outlet and thesubstantially large opening, whereby the gas or air pressure created inthe chamber at the substantially large opening is caused to pass out ofthe said chamber through the said restricted discharge-outlet,substantially as and for the purpose specified.

3. In an electric cut-out or circuit-controller, a base provided with achamber intermediate of its ends having a substantially large opening,and a restricted discharge-outlet for said chamber, a cover for saidbase normally closing said substantially large opening and provided witha gas-outlet adapted to communicate with the restricted discharge-outletof the said chamber, circuit-terminals on 01)- posite sides of saidchamber, and a fuse normally connecting said circuit-terminals andextended across the substantially large opening and across thedischarge-outlet for the chamber between the outlet in the wall of thechamber and the outlet in the cover, substantially as and for thepurpose specified.

4:. In an electric cut-out or circuit-control ler, a base provided witha substantially large chamber having a substantially large opening and aseparate contracted or substantially small outlet or discharge opening,circuit-terminals carried by said base, and a fuse connecting saidterminals and extended across both the discharge opening or outlet andthe substantially large opening to effect a cutting or rupturing of theare, which may be formed between the terminals, by the gases orairpressure created by the melting of the fuse in the substantiallylarge opening, forced out through the substantially smalloutlet-orifice, for the purpose specified.

5. In an electric cut-out or circuit-controller, a base consisting of abottom and side Walls, cross partitions or walls 12 b and top walls 6 bcooperating with the bottom and side walls of the base to form a chamberB provided with outlet or discharge openings in the top walls 12 Z), acover secured to said base and provided with outlets communicating withthe discharge-openings for the chamber B, circuit-terminals secured tothe base on opposite sides of the chamber B, and a fuse connected tosaid terminals and extended across the discharge-openings for the saidchamber, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

NORMAN MARSHALL.

Witnesses:

J AS. H. CHURCHILL, J. MURPHY.

